Is it possible to define a dynamically named property using object literal in JavaScript?

Question

Consider the following

var a = {foo: \"bar\"};

Equivalent to

var a = {};
a.foo = \"bar\";

Equivalent to

Answer 1

JavaScript

var a, b;
(a = {})[b = 'foo'] = 'bar';

CoffeeScript

(a = {})[b = 'foo'] = 'bar'